Alloy and manufactures



Patented Mi, 3, 1933 UNITED STATES jauavtz ALLOY AND MAMUFAOTUBES. Vlevolod Nicholas Krivobok, Pittsburgh, Pa., as-

slgnor, by mesne assignments, to Bustiers and Steel Corporation poration of Delaware No Drawing.

rial No. 707,613. Ben

9Claims.(

This invention relates to austenitic chromiumnickel alloy irons and steels and to articles and manufactures of the same. 1

Among the objects of my invention is-the production of alloy irons and steels, which are' strong, tough, ductile and'readily workable, as by forging. upsetting and piercing, or by hot or cold "rolling, into sheet, strip and bar stock, which readily lends itself to a variety of working and forming operations, such as drilling, machining, punching, blanking, deep-drawing, spinning and welding to achieve a great number of products or manufactures, such as tubing and piping, fluid valves, flanges and bolts, pans, vats and tanks, all for high temperature duty, as in stills, evaporator units and the like, for semichemical uses in the canning, dairy, oil and photographic film industries, or as in chemical calciners used in the production of paints and dyes, or for valves, valve seats, exhaust manifolds,

stacks and the like, as in internal combustion engines, especially automobile and airplane engines, or for buckets, nozzles and like parts for gas turbines, or like articles, products or manufactures for like high temperature applications.

The invention accordingly consists in the combination of elements, composition of ingredients and mixture of materials, and in the articles, products and manufactures thereof, as described herein, the scope of the application of which is indicated in the following claims. As conducive to a clearer understanding of certain features of my invention it maybe noted at this point that the austenitic chromium-nickel irons and steels (irons and s'teels containing approximately, 10% to 25% chromium, 7% to 15% nickel, and the balance substantially iron) are used in the production of a wide variety of corrosion-resistant and mildly heat-resistant products or articles -of manufacture. Thus, these austenitic irons and steels, especially the'18-8 irons and steels (irons and steels containing 18% chromium, 8% nickel, and. the balance substantially iron) may be used in a number of interior or exterior architectural applications, such as decorative trim, ornamentation and fixtures.

Likewise, these irons and steels may be employed for a variety of kitchen, soda fountain, dairy and hospital applications, as in cooking and serving utensils,'containers and appliances, counter and furniture trim and the like, where permanently bright corrosion-resistant metal capable of with standing the corrosive action of various fruit and vegetable acids, is desired. Similarly, these 55 irons and steels are widely adapted for various Iron. Baltimore, Md., a cor- Application January 20, 1934, Se-

ewed January 8, 1988 chemical plant apparatus and equipment where metal resistantto the corrosiveattack of acids,- alkalies and salts at room temperature or slightly eievated temperatures, is required.

These austenitic chromium-nickel irons and steels, however, are not satisfactorily adaptable to extremelyhigh temperature duty, especially high temperature duty under strongly oxidizingv or corrosive conditions.

One of the objects of my invention is the pro- 10 duction of strong, tough and ductile austenitic irons and steels of especially high heat-resistant characteristics, which are resistant 'to scaling, pitting, intergranular corrosion, wear and-abrasion at high temperatures, which may be read- 5 ily worked or formed into a variety of products, articles or manufactures, a number of which are set forth above, particularly adapted to withstandlong peri ds of continuous operation at high temperatures and under the many varying 20 conditions encountered in actual, practical use.

Referring now more particularly to the'.-practice of my invention, alloy iron or steel analyzing approximately, 18% chromium, 8% nickel, 1% to5% molybdenum, 5% to 5% cobalt, .03% to .4% carbon, and the balance substantially iron, with the usual percentages oi'silicon, sulphur and phosphorus, is produced in a suitable manner, as for example, as described in Patent No. 1,925,182 of Alexander L. Feild, entitled Proc- '0 cess for the manufacture of rustlcss iron.

In the production of my alloy iron and steel the metal is first produced as ingots whichare fashioned into blooms or billets in accordance with known methods andcconveniently' hot rolled into sheet bar and strip bar sizes. These bars are then annealed and pickled and, for example, cold rolled into sheet or strip of desired thickness. Myalloy iron and steel-is corrosion-resistant and heat-resistant, withstanding the ex-v o acting conditions of high temperature duty over long periods of continuous use without grain. growth, fatigue or failure. For example, a bar of this austenltic chromium-nickel iron analyzing approximately 18% chromium, 8% nickel, 3% molybdenum, 2% cobalt, '.10% carbon, and the balance substantially iron, subjected to a stress of 8,000 pounds per square inch at a temperature of 1500. l under oxidizing atmospheric conditions has a life of about 350 hours. Ordinary 18-8 chromium-nickel iron analyzing approximately, 18% chromium, 8% nickel, .0'l% carbon, and the balance substantially iron has a life of only about 12 hours to 14 hours under like conditions of. operation. 5

sheet, strip or bar stock. The metal may be forged, upset or pierced, it may be hot or cold rolled into sheet, strip and bar stock, which may be further worked or formed, as by drilling, ma-

chining,'punching, blanking, deep-drawing, spinning and like operations followed by welding where desired, either with the oxy-acetylene torch or with the electric arc (employing welding rods of approximately the same analysis as the stock welded) to achieve a great many articles, productsand manufactures, such as tubing, fluid valves, couplings, flanges and bolts, tanks, trays and pans, all for high temperature duty, as in boilers, condensers, oil cracking stills, evaporator units and the like, or for semi-chemical uses in the canning, dairy, oil and photographic film industries, or for chemical calciners as used in the production of iron-free chemicals, such as paints and dyes under a variety of corrosionfostering conditions, including in addition to the gases normally present in the atmosphere, the sulphur-bearing gases and vapors encountered in -oil stills and oil handling equipment, the mineral waters met with in boiler and condenser applications and like corrosive, embrittling and fatiguing conditions. (The various welded parts, articles or manufactures are preferably heat treated in accordance with well known methods to establish a fully austenitic condition of the metal after the welding is completed in order to molybdenum, 5% to 5% cobalt, .03% to .4% car--' prevent intergranular corrosion and assure maximum chemical resistance in actual use.)

In addition, my austenitic chromium-nickel alloy metal stock may be worked or formed, as above indicated, achieving a further variety of high temperature duty articles, parts and ac- .cessories, such as internal combustion engine valves, valve seats, exhaust manifolds, stacks, especially applicable to automotive and aviation duty, or gas-turbine buckets, nozzles and like parts requiring strength, toughness, shock-resistance, corrosion-resistance and scale-resistance underhigh temperature operating conditions.

Thus, it will be seen that there has been provided in this inventiona chromium-nickel alloy and articles, products or manufactures thereof, in which the-various objects hereinbefore noted, together with many thoroughly practical advantages are successfully achieved. It will be seen that the alloy is strong, tough, corrosion-resistant and heat-resistant and that it readily lends itself to worldng or forming into a variety of commercial products or manufactures, a number of which are set forth above, which are especially adapted to withstand continuous high temperature duty over long periods of time and under the many varying conditions of actual, practical use.

While as illustrative of my invention an austenitic chromium-nickel alloy containing approximately, 18% chromium, 8% nickel, 1% to 5% bon, and the balance substantially iron, is $9 cifically described, good results are achieved where the chromium content ranges between 10% U and 25% and the nickel content between 7% and 15%. In my chromium-nickel alloy irons and steels, as in heretofore known and/or used austeniti'c chromium-nickel irons and, steels, carbon is not an essential ingredient. In fact this element is present only because of the commercial i'mpracticability of ridding the metal of its presence. Ordinarily, at the present time, metal with a carbon'content of from about .03% to .10% is produced without diilloulty although in some melting processes the carbon may amount to as much as .2%, .3% or even .4% as indicated above. As in known austenitic irons and steels, and in articles" and manufactures of the same, metal of the lower carbon contents is preferred for most purposes; the higher carbon steels bein preferably employed in a variety of cast articles or manufactures, such as furnace parts, ore treating and hand ing apparatus, high temperature conveyor parts and equipment, and like parts and equipment subjected to corrosive and abrasive conditions in operation at high temperatures.

Certain practical advantages in achieving longlife austenitic iron and steel at unusually high operating temperatures are achieved by adding theifurther supplemental ingredients, silicon and aluminum, in amounts up to about 3%; these supplementing amounts of silicon and aluminum areemployed either separately or in combination as desired. These ingredients do not materially detract from the physical properties of the metal and directly contribute to the resistance to sealsentially austenitic in structure, of good working characteristics and of good resistance to the corrosive effects of sulphur bearing gases and vapors at high temperatures, containing as essential ingredients 10 per cent to 25 per cent chromium, 7 per cent to 15 per cent nickel, 1 per cent to 5 per cent molybdenum, .5 per cent to 5 per cent cobalt, .03 per cent to .4 per cent carbon, and the balance substantially all iron.

2. In a composition of matter of the class described, high temperature duty iron or steel cssentially'austenitic in structure, of good working characteristics and of good resistance to the corrosive effects of sulphur bearing gases and vapors at high temperatures, containing as essential in gredients approximately, 18 per cent chromium, 8 per cent nickel, 1 per cent to 5 per cent molybdenum, .5 per cent to 5 per cent cobalt, .03 per cent to .4-per centcarbon, and the balance substantially alliron.

3. In a composition of matter of the class described, high temperature duty iron or steel essentially austenitic in structure, of good working characteristics and of good resistance to the corrosive effects of sulphur bearing gases and vapors at high temperatures, containing as essential ingredients-approximately, 18 per cent chromium,

8 per cent nickel, 3 per cent molybdenum, 2 per cent cobalt, .10 per cent carbon, and the balance plications where corrosive or corrosion fostering media are encountered, containing as essential ingredients approximately, 18 per cent chromium, 8 per cent nickel, 1 per cent to 5 percent molybdenum, .5 per cent to 5 per cent cobalt, .03 per cent to .4 per cent carbon, and the balance substantially, all iron.

5. In manufactures of, the class described, high temperature duty iron or steel sheet, strip or bar stock essentially austenitic in structure and of good resistance to the effects of iron and sulphur bearing vapors at high temperatures, containing as essential ingredients 10 per cent to 25 per cent chromium, '7 per cent to 15 per cent nickel, 1 per cent'to 5 per cent molybdenum, .5 per cent to 5 per cent cobalt, .03 per cent to .4 per cent carbon, and the balance substantially all iron.

6. In manufactures of the class described, high temperature duty austenitic iron or steel welded articles, products and manufactures containing as essential ingredients approximately, 18 per cent chromium,- 8 per cent nickel, 1 per cent to 5 per cent molybdenum, .5 per cent to 5 per cent cobalt, .03 per cent to .4 per cent carbon, and the balance substantially all iron.

'7. In manufactures of the class described, high temperature duty austenitic iron or steel tubes containing as essential ingredients approximately, 18 per cent chromium, 8 per centnickel, 3 per cent molybdenum, 2 per cent cobalt, .10 per cent carbon, and the balance substantially all iron.

8. In manufactures of the class described,

stock of good resistance to the corrosive attack of air and sulphur bearing gases at high temperatures, containing as essential ingredients approximately, 10 per cent to 25 per cent chromium,

7 per cent to 15 per cent nickel, 1 per cent to 5 per cent molybdenum, .5 per cent to 5 per cent cobalt, and the balance substantially all iron.

VSEVOLOD NICHOLAS KRIVOBOK. 

